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Background: The menstrual cycle is a health indicator in women. The change in health makes female students feel less confident in communicating, studying, and living. Therefore, the study on the characteristics of the menstrual cycle in female medical students brings many practical meanings by figuring conclusions and solutions to improve both physiological and mental discomforts for women during menstruation. Objectives: Can Tho University of Medicine and Pharmacy (CTUMP) 3rd year medical students were studied for the characteristics, the abnormalities of the menstrual cycle, and the premenstrual syndrome. Materials and methods: The design of a cross-sectional descriptive study with analysis by direct interview method was conducted on 126 female 3rd year medical students at CTUMP. Results: Long menstrual cycle time accounted for 38.1% of subjects, while short menstrual cycle time accounted for 0.8%. The study also found that the average menstrual period was 5.00±1.34 days. The premenstrual syndrome was observed in 47.3% of students, with abdominal pain and low back pain accounted for the highest rate (63.5%), and headache accounted for the lowest rate (9.5%). Menorrhagia had a low prevalence (7.1%), whereas menstrual cramp was much more common (60.3%). Conclusions: Long menstrual cycles occurred at a high rate among medical students. Abdominal pain and low back pain were the most common symptoms before menstruation. Menstrual cramp was the most common abnormality of the menstrual cycle among CTUMP female medical students.

Transparent MgAl2O4 ceramics were fabricated by pulsed electric current sintering (PECS) employing two-step sintering mode. First, nanoscale MgAl2O4 powders were produced by solution combustion synthesis from hydrated nitrate compounds and urea. Subsequently, the synthesized powders were sintered by PECS with a heating rate of 100oC/min under an applied pressure of 100 MPa. The sintering process was conducted according to two-step heating profile. At the first step, the temperature increased to 1050, 1100, and 1150oC, followed by a dwell time of 60 min. The second-step sintering was carried out at 1300, 1350, and 1400oC for 20 min. The transparent ceramics sintered at 1050oC/ 60 min – 1400oC/ 20 min exhibited transmittance over 80% in infrared range. In addition, transparent samples presented a Vickers hardness up to 30 GPa for sintering mode of 1150oC/ 60 min – 1400oC/ 20 min.

An effective diffusion barrier layer was coated onto the surface of BiTe-based materials to avoid the formation of brittle intermetallic compounds (IMCs) by the diffusion of the constituents of Sn-based solder alloys into the BiTe-based alloys. In this study, the electrochemical deposition of multi-layers, i.e., electroless nickel/electroless palladium/immersion gold (ENEPIG) was explored to enhance the bonding strength of BiTe materials with Cu electrodes. The thermoelectric modules with the ENEPIG plating layer exhibited high bonding strengths of 8.96 MPa and 7.28 MPa for the n- and p-type, respectively that increased slightly to 9.26 MPa and 7.76 MPa, respectively after the thermoelectric modules were heated at 200 °C for 200 h. These bonding strengths were significantly higher than that of the thermoelectric modules without a plating layer.

The objective of the present work is to investigate the feasibility of the synthesis of copper matrix composite reinforced with in-situ nanosized Al2O3 particle powder via combustion synthesis method from metal nitrates followed by reducing process at high temperature. The starting nitrates Cu(NO3)2.3H2O and Al(NO3)3·9H2O composition corresponds to Cu-30%Al2O3. X-ray Diffraction (XRD) patterns of the obtained powders indicated the presence of the oxides CuO and CuAl2O4. The powder had the size of 75 ± 10 nm after deagglomerating by soft ball milling for 24h. After reducing in CO at 1000oC for 3h, the peaks of the oxides were no longer observed and were replaced by the peaks of Cu and -Al2O3. The morphology of the reduced powders observed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis showed well distribution of the -Al2O3 particles within the Cu matrix with an average particle size of 40 nm.

To produce BiTe-based thermoelectric modules, BiTe-based species with an electroless NiP (EN) coating layer acting as a diffusion barrier were connected to Cu electrodes by a soldering process. In order to investigate the thermal stability of the EN diffusion barrier on BiTe-based thermoelectric materials, Ni-coated BiTe-based modules were annealed at 200 °C for 200, 500, and 1000 h. The bonding strength of the BiTe species was >8 MPa, and it remained stable after 200, 500, and 1000 heating hours. The interfacial structure indicated the formation of a Sn–Cu intermetallic compound (IMC) below the EN-plated region. The morphology of Sn–Cu IMC before and after heating was observed. As the current flow was applied through the BiTe-based thermoelectric module, the temperatures on the hot and cold side of the modules were recorded. Owing to the thermal stability of the EN layer, the 200 h heated modules presented heating and cooling efficiencies similar to those of non-heated modules.

Whether state ownership can affect the behaviour of corporations is an important research question, especially in a context such as severe recession or pandemic where policy makers have to consider bailing out large companies, thus increasing state ownership in corporations. This study investigates the impact of state ownership on corporate risk‐taking in Vietnamese listed firms. We find that state ownership is positively associated with corporate risk‐taking. The findings suggest that state ownership may encourage excessive risk‐taking, which has implications for policy makers when they consider increasing state ownership in corporations. We argue that state ownership representatives in Vietnamese corporations tend to take excessive risks to facilitate their personal gains, consistent with the prediction of the double‐agency problem hypothesis. We highlight the important role of a monitoring mechanism, which can mitigate this agency problem. We find that foreign ownership moderates the relationship between state ownership and risk‐taking in Vietnamese firms, consistent with the usefulness of a corporate‐governance mechanism in mitigating the double‐agency problem.

The deteriorating nature of severe functional tricuspid regurgitation (FTR) has led to the heightened interest in this pathology. However, therapies are heterogeneous and an ideal technique is uncertain. The hemodynamic impact on the cardiac chamber following therapeutic repairs has not been well studied, while its analysis could be used to predict the treatment success. In this study, the hemodynamics of the right ventricle (RV) after 1) clover edge-to-edge tricuspid repair, and 2) double orifice tricuspid repair was evaluated in three right heart models using an ex vivo pulsatile platform emulating severe FTR with the aid of stereoscopic particle image velocimetry. Although all repairs substantially reduced tricuspid regurgitant area, they resulted in a more than 50% reduction in diastolic tricuspid valve (TV) opening area. Splitting the TV orifice into multiple smaller orifices by both repairs eliminated the ring-shaped vortical structure inside the RV observed in FTR cases. Postrepair RV domain was mostly occupied with irregular vortical features and isolated vortex residuals. Moreover, vortical features varied among repair samples, indicating enhanced sensitivity of RV flow to postrepair TV morphology. Compared with clover repair, double orifice subjected the RV to enhanced swirling motions and exposed more regions to vortical motions, potentially indicating better rinsing and lower risk of mural thrombus formation. Double orifice repair increased the levels of RV mean kinetic energy and viscous energy loss than those observed in clover repair, although the impact of these on the cardiac efficiency remains unclear. These preliminary insights could be used to improve future treatment design and planning. NEW & NOTEWORTHY While clover and double orifice tricuspid repairs markedly improved leaflet coaptation, they substantially reduced diastolic tricuspid opening area. Postrepair right ventricle (RV) exhibited specific hemodynamic traits, including the loss of ring-shaped vortical structure and the enhanced sensitivity of RV flow to postrepair tricuspid valve morphology. Compared with clover technique, double orifice repair led to higher swirling motions in the RV domain, which could indicate lower risk of mural thrombus formation.

Financial systems are complex and may support economic growth differently at various stages of economic development. This study of 90 countries extends the financial development-economic growth literature by using four proxies of financial development (banking, stock market, bond market and insurance), and considering a country’s level of economic development, on both a full and pre-global crisis sample. As expected financial markets have different effects on growth where the level of economic development vary. Policy makers should find that the insurance sector offers the most benefit for economic growth at all levels of development. Stock markets promote growth for middle income countries. Similarly bond markets promote growth with middle and high income countries. Some bond market and stock market results differed in the pre-crisis sample. Policies which promote trade but limit other areas such as inflation, government consumption and crises, should also support growth.

There has been a resurgence of interest in the treatment of severe functional tricuspid regurgitation (FTR) due to the awareness of its poor outcomes and potential percutaneous therapies. Kay bicuspidization has been adapted in percutaneous therapies but its clinical outcome remains uncertain. The present study evaluates the efficacy of Kay repair in a novel ex vivo pulsatile system. Porcine tricuspid valve (TV) (n = 3) was extracted and incorporated into a patient-specific silicon right ventricle (RV) emulating severe FTR, on which Kay repair was subsequently performed. TV area metrics and RV hemodynamic assessment by means of stereo-scopic particle image velocimetry were quantified in both FTR and post-repair conditions. Bicuspidization led to significant increase in cardiac output although the overall increment due to this approach alone was generally small, possibly due to existence of residual TR and the large reduction in TV opening area. Kinetic energy and viscous loss levels were increased post-repair, especially during diastolic filling. Main vortex structures generally maintained post-procedural. However, there was enhanced swirling motion in larger RV domain. Although this might reduce mural-thrombus risk, the relatively more complex vortex phenomenon likely resulted in elevated viscous loss observed and may potentially impact long-term adaptation. The RV hemodynamic alteration after tricuspid repair could be used to predict the success of these future transcatheter solutions.

Highly porous alumina (Al2O3) was prepared by sintering of Al2O3 powder using ammonia bicarbonate (NH4HCO3) as a pore-forming agent and chromia (Cr2O3) as a sintering additive. In order to investigate the influence of particle shape and size on the characterization of sintered porous Al2O3, the starting Al2O3 powders included commercial disk micro-sized powder and synthesized spherical nanopowder. The nanoscale Al2O3 powder was produced via combustion synthesis route. At the optimal pore-forming agent concentration, the porous Al2O3 sintered by nanoparticles had a smaller pore size and a lower total porosity than the one prepared by microparticles. The differences of open porosity and closed porosity between porous Al2O3 synthesized by micro and nano-scale powders with and without Cr2O3 dopant were also discussed. In addition, the compressive strength of porous Al2O3 achieved by nano-sized powders, especially with Cr2O3 dopant, had a higher value in comparison with the one prepared by micro-sized powders.

We study the relationship between the foreign exchange risk and analyst target price forecast error using U.S. firm-level data for the sample period between 1999 and 2014. We find that the target price forecast error is higher when foreign exchange risk is higher. The relationship is stronger for smaller firms and less pronounced among financial firms. Collectively, the findings suggest that analysts make fewer errors when forecasting for firms that are more capable of managing foreign exchange risks. These findings imply that either analyst does not make a significant effort in incorporating foreign exchange risk into their forecast models, or they do not have the skills for that task.

Fifty-pair Bi2Te3-based thermoelectric (TE) modules were produced by spreading Sn alloy solder on Cu electrodes before heating at 270℃ for 10 min to connect Bi2Te3-based legs with Cu electrodes. To suppress unexpected reactions between solder and TE materials, a conventional electroless nickel (EN) layer and a novel coating encompassing EN, electroless palladium, and immersion gold (ENEPIG) layers were adopted for Bi2Te3 materials as diffusion barriers. Influence of variant diffusion barriers, namely, EN and ENEPIG, on TE performance of module was ascertained. Interfacial structure at Bi2Te3/solder/Cu electrode interface revealed that intermetallic compounds were generated owing to interdiffusion among Cu, Sn, and coating elements, and they mostly concentrated at Bi2Te3/solder and solder/Cu electrode interfaces. Additionally, ENEPIG coating exhibited much better wettability with solder than the EN coating, resulting in fewer defect sites at Bi2Te3/solder interface. When current flowed through TE modules, the ENEPIG-coated module yielded lower temperatures on both hot and cold sides than the EN-coated module. While the modules had temperature differences between two substrates, output power generated by the ENEPIG-coated module was higher than that of the EN-coated module. In addition, the ENEPIG-coated module showed a smaller internal resistance than the EN-coated module. After heating at 200℃ for 200 h, both modules presented markedly reduced output power, whereas internal resistance was escalated.

An electroless nickel (EN) layer and EN, along with electroless palladium (EP), and immersion gold (IG) (ENEPIG) multilayers were two variant diffusion barriers employed for Bi2Te3-based thermoelectric materials. After the electroless plating process, coated Bi2Te3-based species were bonded with Cu electrodes using a soldering method with Sn-based alloy as a solder. Heat treatment was conducted at 200 °C for 200, 500, and 1000 h to investigate the thermomechanical stability of the Bi2Te3/solder interface adopting different coatings. First, the Bi2Te3/solder interface characteristics were analyzed by compositional identification and morphology observation. Intermetallic compounds (IMCs) were generated below the plating area in both EN and ENEPIG. The phase composition of these IMCs was identified by qualitative analysis. Additionally, the thickness of IMCs with ENEPIG was larger than those with EN regardless of annealing duration. The IMC morphology without and with 200 h of heating showed columnar grains, while those with heating over 500 h exhibited equiaxed grains. The ENEPIG coating generally yielded a higher bonding strength for the Bi2Te3/solder interface than the EN layer. Meanwhile, the bonding strength for EN and ENEPIG was constant after 200 h of heating, followed by a significant drop at 500 h, and it finally leveled off after heating for 1000 h. Furthermore, the fracture caused by the shear test was characterized by the brittle fracture mode. Ultimately, the IMC morphology was found to influence the bonding strength along with the increase in annealing duration rather than IMC thickness and composition.

In a healthy human cardiac system, a large asymmetric clockwise vortex present in the left ventricle (LV) efficiently diverts the filling jet from the mitral annulus to the left ventricular outflow track. However, prior clinical studies have shown that artificial mitral valve replacement can affect the formation of physiological vortex, resulting in overall flow instability in the LV. Lately, the findings from several recent hemodynamic studies seem to suggest that the native D-shaped mitral annulus might be a crucial factor in the development of this physiological flow pattern, with its inherent flow stability and formation of coherent structures within the LV. This study aims to investigate the effect of orifice shape and its position with respect to the posterior wall of the ventricle on vortical formation and turbulence intensity in the LV, by utilizing four separate orifice configurations within an in vitro left heart simulator. Stereo particle image velocimetry experiments were then carried out to characterize the downstream flow field of each configuration. Our findings demonstrate that the generation of the physiological left ventricular vortical flow was not solely dependent upon the orifice shape but rather the subsequent jet-wall interaction. The distance of the orifice geometric center from the left ventricular posterior wall plays a significant role in this jet-wall interaction, and thus, vortical flow dynamics.

The diffusion barrier layers in thermoelectric generators (TEGs) are widely used to improve their mechanical/thermal stabilities and energy generation performance; however, thickness dependence of diffusion barrier was rarely reported. In this study, we prepared Bi2Te3-based thermoelectric (TE) modules and Ni diffusion barrier with a thickness of 0–30 µm to investigate the correlation between the thickness of Ni layers and TE output performance. A TE module with 1 μm-thick Ni layer harvests a maximum output power of 2.79 mW under a temperature difference (ΔT) of 200 K, which is a higher value than that of a module without a diffusion barrier. Regarding the dependence of TE output performance on the diffusion barrier’s thickness, TEGs based on the thicker Ni layers showed lower output performance for all ΔT ranges compared with a 1 µm-Ni layer TEG. The degradation of TE conversion efficiency was related to the increment of contact resistance (Rc) with the thickness of the diffusion barrier. This Ni thickness-dependent Rc was explored using the transmission line method. The results from this study prove that the thickness of optimized diffusion barriers would maximize the output performance of TEGs, which could be used as a guide for improving the performance of TEGs.

The concept of heterotopic implantation of transcatheter tricuspid valve is new and has shown promising results thus far. While the Reynolds shear stress values measured in the vicinity of this valve are relatively low, the values at some time points are higher than the threshold of platelet activation. Hence, in this study, we aim to reduce these values with an innovative stent design. It was shown that the Reynolds shear stress values measured were lower than those of valves made of generic stent design and the maximum Reynolds shear stress values in the vicinity of the valves was very low (∼10 dynes/cm2 ). The results also depicted the interesting flow phenomenon of this non-physiological treatment approach. Thus, this study has shown that bicaval valves could potentially be considered as a minimally invasive option to treat tricuspid regurgitation and valve design improvements could reduce the flow disturbances that were observed.

The increased understanding of right heart diseases has led to more aggressive interventions to manage functional tricuspid regurgitation (FTR). In some cases of FTR, prosthetic valve replacement is typically considered when concomitant organic components or significant geometrical distortions are involved in the pathology of the tricuspid valve. However, little is known of the performance of current devices in the right heart circulation. In this study, a novel in vitro mock circulatory system that incorporated a realistic tricuspid valve apparatus in a patient-specific silicon right ventricle (RV) was designed and fabricated. The system was calibrated to emulate severe FTR, enabling the investigation of RV hemodynamics in pre- and post-implantation of tri-leaflet tissue implant and bi-leaflet mechanical implant. 2D particle imaging velocimetry was performed to visualize flow and quantify relevant hemodynamic parameters. While our results showed all prosthetic implants improved cardiac output, these implants also subjected the RV to increased turbulence level. Our study also revealed that the implants did not create the optimal behavior of fluid transfer in the RV as we expected. Among the implants tested, tissue implant created the most dominant vortices, which persisted throughout diastole; its observed strong negative vortex could lead to increase energy expenditure due to undesired fluid direction. In contrast, both native valve and mechanical implant had both weaker vortex formation as well as more significant vortex dissipation. Interestingly, the vortex dissipation of native valve was associated with streamlined flow pattern that tended towards the pulmonary outlet, while the mechanical implant generated more regions of flow stagnation within the RV. These findings heighten the imperative to improve designs of current heart valves to be used in the right circulation.

Heterotopic implantation of transcatheter tricuspid valve is a new treatment option for tricuspid regurgitation. Transcatheter tricuspid valves (inferior and superior) are implanted at the cavo-atrial junctions (CAJ) in order to avoid the challenging task of anchoring the valve in the complex tricuspid valve annulus. However, little is known about the complex loading that the valve stent can withstand at the cavo-atrial junction, which is critical for fatigue life prediction and device development. In this study, we developed a finite element based fatigue model taking into account the major fatigue loads that may be acting upon the two caval stents, after deployment. The simulation results showed that both stent designs had a fatigue safety factor (FSF) greater than 1 under these complex loading conditions. It was also observed from our simulation that leaflets loads contributed more towards the fatigue of valved stents compared to the other loads. The fatigue model presented in this study provides a simple, fast and cost-effective tool to quantitatively determine the fatigue resistance of caval valved stents subjected to cyclic loads. The simulated bench testing proposed here can be of great value to the design and development of new prosthetic cava stented valves.

Transparent MgAl 2 O 4 ceramic could be found in a wide range of applications for both military and civil sector due to its high melting point, good mechanical properties, small refractive index (1.71) and its ability to allow light in range from UV to mid-IR to pass through. In the present work, transparent MgAl 2 O 4 was fabricated from metal nitrates via two steps. Firstly, the MgAl 2 O 4 nanopowder was synthesized via solution combustion synthesis from the metal nitrates. Secondly, the powder was then consolidated by Pulsed Electric Current Sintering (PECS) technique to fabricate transparent ceramic. XRD patterns of the obtained powder showed the peaks of only MgAl 2 O 4 phase. Besides, the atomic compositions of magnesium, aluminium and oxygen determined by EDX analysis were approximately corresponded to 1:2:4 of the molecular formula of MgAl 2 O 4 . After deagglomerating for 48 hours using soft ball-milling, the powder had the average particle of 27 nm. Transparent MgAl 2 O 4 samples, which were sintered with two-step sintering mode of 1050 o C/60 minutes-1400 o C/20 minutes, permitted the transmission of visible and infrared light with the transmittance up to 80%, Vickers hardness of 14.2 GPa, and fracture toughness of 1.1 MPa.m 1/2 . The results are a critical step toward fabrication of high-quality transparent ceramics from metal nitrates.

In this study, an electroless nickel (EN), electroless palladium (EP), and immersion gold (IG) (ENEPIG) multilayer coat was developed for application on BiTe-based thermoelectric materials to increase the bonding strength between BiTe-based materials and Cu electrodes in thermoelectric modules. The ENEPIG-plated thermoelectric module exhibited a bonding strength of over 11 MPa, which was approximately 40% higher than those of conventional EN-plated modules. According to the interfacial analysis of the bonding areas via a field emission electron probe micro analyzer (FE-EPMA), the Ni layers in ENEPIG and EN acted as diffusion barriers to inhibit the formation of brittle Sn-Te intermetallic compounds (IMCs). Sn-Cu-Pd and Sn-Cu IMCs were formed below the Ni-plated area at the bonding interface of the ENEPIG and EN-plated modules, respectively. However, Sn-Cu-Pd IMCs in the ENEPIG interface exhibited thicker and more homogeneous IMC layers after heat treatment compared to the Sn-Cu IMCs in the conventional EN interface. The wettability of the ENEPIG-plated BiTe surface was significantly greater than that of the EN-plated surface. This directly induced fewer and smaller pores on the bonding interface of the BiTe-based materials with ENEPIG plating compared to those with EN plating, thereby resulting in the higher bonding strength of ENEPIG-plated modules.

Heterotopic implantation of transcatheter tricuspid valve is a new treatment option for tricuspid regurgitation. Transcatheter tricuspid valves are implanted onto the cavoatrial junction in order to avoid the challenging task of anchoring the valve onto the complex tricuspid valve annulus. However, little is known about optimum extent of oversizing of the valved stent in a vena cava. In this study, we implanted valves of the same diameter onto the larger sized inferior vena cava (IVC) and a smaller sized superior vena cava (SVC). The valve in the IVC was oversized by 10.7% while the valve in the SVC was oversized by 21.6%. Finite element analysis was performed (i) to assess the strain on the nitinol stent during manufacturing and deployment; (ii) the stents were deployed in a patient-specific vena cava model and the intramural stress of the vena cava was calculated computationally. These valves were fabricated and placed in a silicone model of a patient-specific right atrium which was part of a mock circulatory system that emulated the patho-physiological flow rate and pressure of a patient with tricuspid regurgitation. Flow measurements were conducted by particle image velocimetry (PIV). It was found that the maximum crimping strain on the nitinol stent was 6.85% which was lower than the critical threshold of 10%. The maximum stress on the vena cava was located at the spot where the hooks met the wall. The maximum stress on the IVC was 0.5098 MPa while the maximum stress on the SVC was 0.7 MPa. The maximum Reynolds shear stress (mRSS) in the vena cava was found to be higher in the IVC than SVC with the highest mRSS being 1741 dynes/cm(2) found in the region of high flow during the peak flow phase. The overtly oversized valve in the SVC did not cause flow disturbances and exhibited mostly laminar flows. The mRSS at the downstream of the vena cava valve and the middle of the atrium remained at low magnitudes. However, velocity fluctuations were high in the IVC in all the time points measured. In conclusion, oversizing the valve may assist anchorage; yet, careful consideration should be taken in choosing the extent of oversizing as it may lead to adverse effects.

Intra-ventricular flow dynamics has recently emerged as an important evaluation and diagnosis tool in different cardiovascular conditions. The formation of vortex pattern during the cardiac cycle has been suggested to play important epigenetic and energy-modulation roles in cardiac remodelling, adaptations and mal-adaptations. In this new perspective, flow alterations due to different cardiovascular procedures can affect the long-term outcome of those procedures. Especially, repairs and replacements performed on atrioventricular valves are likely to exert direct impact on intra-ventricular flow pattern. In this review, current consensus around the roles of vortex dynamics in cardiac function is discussed. An overview of physiological vortex patterns found in healthy left and right ventricles as well as post-operative ventricular flow phenomenon owing to different atrioventricular valvular procedures are reviewed, followed by the summary of different vortex identification schemes used to characterise intraventricular flow. This paper also emphasises on future research directions towards a comprehensive understanding of intra-cardiac flow and its clinical relevance. The knowledge could encourage more effective pre-operative planning and better outcomes for current clinical practices.

Severe tricuspid regurgitation (TR) is life-threatening but is often undertreated. Many patients with severe TR are denied heart valve replacement surgery because their old age or comorbidities predispose them to a higher risk of surgical complications associated with open-heart surgery. With the advent of transcatheter technology, it is now possible to deliver the valve to the desired location without the need for open-heart surgery. However, presently, there is no commercially available transcatheter tricuspid valve. This may be due to the complex tricuspid valve anatomy, which lacks an anchorage zone for the percutaneous valves. In view of this drawback, we have recently developed and tested two percutaneous caval heart valves that are designed to deploy at the vena cava and atrium junction. The hemodynamic characteristics of these valves are tested in a mock circulatory system with patient-specific silicone atrium and vena cava, which emulates the physiological pressure and flow conditions at the right side of the human heart. Particle imaging velocimetry results showed that flow velocity and the associated Reynolds shear stress (RSS) and the turbulent kinetic energy (TKE) downstream of the valves increased after the implantation of the valves. A maximum flow velocity of 0.94 m/s was observed at the region downstream of the percutaneous valve at the superior vena cava (SVC). Maximum RSS value of 2076.1 dynes/cm(2) was observed downstream of the valve at the inferior vena cava during the deceleration phase while maximum TKE measured was 572.6 J/m(3) at the upstream of the valve in the SVC during the peak flow phase. While these values appear high, they are significantly lower than those reported in prosthetic mitral and aortic valves. Hence, caval stented valves can be potentially considered as a minimally invasive option to treat TR.

The concept of heterotopic implantation of transcatheter tricuspid valve is new and has shown promising results thus far. While the Reynolds shear stress values measured in the vicinity of this valve are relatively low, the values at some time points are higher than the threshold of platelet activation. Hence, in this study, we aim to reduce these values with an innovative stent design. It was shown that the Reynolds shear stress values measured were lower than those of valves made of generic stent design and the maximum Reynolds shear stress values in the vicinity of the valves was very low (∼10 dynes/cm

There has not been much progress in the development of transcatheter tricuspid valves to treat tricuspid regurgitation because of the difficulty in anchoring a stented valve onto the complex tricuspid annulus. Hence, the concept of heterotopic implantation of the transcatheter tricuspid valve onto the cavo-atrial junction was proposed. However, to date there has been no detailed in vitro investigation of the hemodynamic performance of this new device. The study utilises both 2-D and 3-D particle image velocimetry (PIV) to interrogate the flow patterns in the vicinity of the extra-cardiac tricuspid valves in an in vitro physiological flow loop, specifically at four measurement locations in the cavo-atrial anatomy. Comparison of the 2-D and 3-D PIV results revealed that accuracy of 2-D PIV would be acceptable at time point and at measurement locations where the velocity was mostly planar with minimal or low out-of-plane flow such as at the outlet of the superior vena cava valve at the point of valve closure. The results also showed that the RSS in the vicinity of the valves were relatively low (∼150 dynes/cm 2 ) with the exception of that in the leakage jet at the upstream of the valve. The leakage in the leaflets could be a result of the use of aortic valve leaflets which was more suited for the higher pressured environment of the left side of the heart. The stent design could also be customised for implantation in the vena cava. In summary, these issues could be eradicated with improvements to the leaflet and stent design which would enhance the haemodynamics of the post-implantation flow performance.

Clotting of blood elements or intraluminal thrombus (ILT) is known to develop within aortic aneurysm sacs, and is clinically associated with the dilation and rupturing of aneurysms. However, the underlying factors that generate ILT are still unclear. We hypothesize that ILT can form under the influence of unfavorable hemodynamic patterns. This paper presents evidence for one such type of flow dynamics that could give rise to ILT within the aneurysm sac. Image-based patient-specific fluid–structure-interaction modeling of three cases of thoracic aortic aneurysms was performed, using retrospective CT images to investigate the formation of ILT as a result of local hemodynamic of aneurysm. This study showed that the formation of the ILT was associated with a vortex observed near the aortic narrowing, upstream of the aneurysm sac. This vortex could subject the blood elements to elevated stresses before directing them into the sac. The recirculation flow within the aneurysm sac may trap these activated blood elements, thus, leading to the formation of ILT during early diastole. One primary cause for ILT, as indicated in this study, could be attributed to the sharp curvature at the aortic narrowing (or isthmus) that gives rise to the vortex. Our study also showed that the size and location of the aneurysm have a direct impact on the duration and location of the vortex, which could influence the formation of the ILT.

Severe tricuspid regurgitation (TR) is life-threatening but is often undertreated. Many patients with severe TR are denied heart valve replacement surgery because their old age or comorbidities predispose them to a higher risk of surgical complications associated with open-heart surgery. With the advent of transcatheter technology, it is now possible to deliver the valve to the desired location without the need for open-heart surgery. However, presently, there is no commercially available transcatheter tricuspid valve. This may be due to the complex tricuspid valve anatomy, which lacks an anchorage zone for the percutaneous valves. In view of this drawback, we have recently developed and tested two percutaneous caval heart valves that are designed to deploy at the vena cava and atrium junction. The hemodynamic characteristics of these valves are tested in a mock circulatory system with patient-specific silicone atrium and vena cava, which emulates the physiological pressure and flow conditions at the right side of the human heart. Particle imaging velocimetry results showed that flow velocity and the associated Reynolds shear stress (RSS) and the turbulent kinetic energy (TKE) downstream of the valves increased after the implantation of the valves. A maximum flow velocity of 0.94 m/s was observed at the region downstream of the percutaneous valve at the superior vena cava (SVC). Maximum RSS value of 2076.1 dynes/cm(2) was observed downstream of the valve at the inferior vena cava during the deceleration phase while maximum TKE measured was 572.6 J/m(3) at the upstream of the valve in the SVC during the peak flow phase. While these values appear high, they are significantly lower than those reported in prosthetic mitral and aortic valves. Hence, caval stented valves can be potentially considered as a minimally invasive option to treat TR.

// Salima Akter 1 , Tae Gyu Choi 1 , Minh Nam Nguyen 1 , Abel Matondo 1 , Jin-Hwan Kim 1 , Yong Hwa Jo 1 , Ara Jo 1 , Muhammad Shahid 1 , Dae Young Jun 1 , Ji Youn Yoo 1 , Ngoc Ngo Yen Nguyen 1 , Seong-Wook Seo 1 , Liaquat Ali 2 , Ju-Seog Lee 3 , Kyung-Sik Yoon 1 , Wonchae Choe 1 , Insug Kang 1 , Joohun Ha 1 , Jayoung Kim 4 , Sung Soo Kim 1 1 Department of Biochemistry and Molecular Biology, School of Medicine, Kyung Hee University, Seoul, Republic of Korea 2 Department of Biochemistry and Cell Biology, Bangladesh University of Health Sciences, Dhaka, Bangladesh 3 Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA 4 Departments of Surgery and Biomedical Sciences, Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA Correspondence to: Sung Soo Kim, e-mail: sgskim@khu.ac.kr Keywords: microarray, gene signature, breast cancer, prognosis Received: December 26, 2014 Accepted: March 10, 2015 Published: April 11, 2015 ABSTRACT Clinical applications of gene expression signatures in breast cancer prognosis still remain limited due to poor predictive strength of single training datasets and appropriate invariable platforms. We proposed a gene expression signature by reducing baseline differences and analyzing common probes among three recent Affymetrix U133 plus 2 microarray data sets. Using a newly developed supervised method, a 92-probe signature found in this study was associated with overall survival. It was robustly validated in four independent data sets and then repeated on three subgroups by incorporating 17 breast cancer microarray datasets. The signature was an independent predictor of patients’ survival in univariate analysis [(HR) 1.927, 95% CI (1.237–3.002); p < 0.01] as well as multivariate analysis after adjustment of clinical variables [(HR) 7.125, 95% CI (2.462–20.618); p < 0.001]. Consistent predictive performance was found in different multivariate models in increased patient population ( p = 0.002). The survival signature predicted a late metastatic feature through 5-year disease free survival ( p = 0.006). We identified subtypes within the lymph node positive ( p < 0.001) and ER positive ( p = 0.01) patients that best reflected the invasive breast cancer biology. In conclusion using the Common Probe Approach, we present a novel prognostic signature as a predictor in breast cancer late recurrences.

Since the 1997 financial crisis many East Asian economies attempted to realign their financial systems to prevent future crises and establish financial mechanisms to better sustain long-term development. This chapter examines the financial system development of select Asia-Pacific countries from before the Asian financial crisis to the present. We highlight the growth of the Chinese financial market and especially the enabling role now undertaken by Hong Kong. In most countries financial market reform and development of stock markets undertaken following the shock of the Asian financial crisis, made these countries more resilient to the global crisis that affected world markets from 2007 onwards.

Prior studies have examined the development of the financial system and its impact on economic growth, but little has been said about the relationship between its four major components: banking, the stock market, the bond market (private and public bond) and insurance (life and nonlife). Using a dynamic panel of 106 countries over the period 1980-2007, we use the GMM (generalized-method-of-moments) system estimator to observe the pair-wise relationships between these components. Our findings show a high level of interdependence. When evaluated at the average level of each component’s development, the majority of the pair-wise relationships reveal that one component will act as a substitute for the other. This should be taken into consideration for policies relating to growth in the financial sector.

While insurance plays an important role in the financial sector, it is often ignored in the financial development-economic growth literature. This paper examines the relationship between insurance and economic growth via a global cross-country study over 1980 to 2006, using both cross-sectional estimations and dynamic panel data techniques. We find a significant positive relationship between economic growth and overall insurance, as well as more specifically for life and non-life insurance. We find weak evidence that a country’s stage of development may influence this relationship; but strong evidence that the quality of a country’s legal system and protection of property rights is positively related to insurance growth. The study adds to the existing literature in respect to the legal factors as well as offers further support for the role of insurance in the finance-growth literature.